1. Field of the Invention
The present invention relates to dive masks and more particularly, to novel systems and methods for relieving facial discomfort and injury caused by the pressure differential between the ambient water and the air inside the dive mask.
2. The Relevant Technology
Diving, as a recreational pastime, has been increasing in popularity recently, as more people seek to experience the wonders of underwater life. Many people snorkel, which involves the use of a tube to breathe air from above the surface of the water while the mouth and nose are immersed. Although some snorkelers remain on the surface of the water, others hold their breath while descending to view wildlife that cannot be observed from the surface.
Many people vacationing near large bodies of water also enjoy SCUBA diving. SCUBA, which stands for xe2x80x9cself-contained underwater breathing apparatus,xe2x80x9d identifies a class of equipment, including pressurized air tanks, buoyancy control vests, and air pressure regulators, that allow people to breathe underwater. The equipment permits a SCUBA diver to remain underwater for far longer periods of time than a snorkeler. Indeed, the recreational SCUBA diver may remain immersed for periods of time over an hour and often descend to depths of up to 100 feet under the surface. Professional divers frequently descend to even greater depths.
An important issue for divers, particularly those who venture to greater depths, is the compression of air spaces in and around the diver as ambient water pressure increases.
Because of water""s weight, the pressure it will exert on an object increases significantly with depth. All air volumes in contact with the diver""s person such as the lungs, the inner ears, and the air space within the dive mask typically start at the surface of the water with a given volume of gas at atmospheric pressure.
As the diver descends into the water, the increase in ambient water pressure imposes loads on all gas volumes. Gas volumes that are not volume-constrained are compressed and reduced in size. Volumes that are constrained in size develop a pressure differential and load across their membrane.
Two important gas volumes that are somewhat volume-constrained are the airspaces of the inner ear and the airspace contained within the dive mask. Pressure loads on the inner ears, the sinuses, the eyes, and the face of the diver can cause discomfort and injury. Injury to the inner ear is avoided by equalizing the pressure in the inner ear. This is done by gently blowing additional air into the inner ear to maintain its volume.
An air space must be maintained within the mask to permit clear underwater vision. The mask is relatively incompressible and is typically sealed to the face by means of a rubber lip. Unless the diver blows additional air into the mask or allows water into it, the pressure against the diver""s face will remain at roughly one atmosphere. Consequently, if the diver breathes exclusively through the mouth while descending, without removing any portion of the mask seal, a pressure differential builds across the skin of the diver""s face.
This is frequently referred to as xe2x80x9cmask squeeze.xe2x80x9d To avoid mask squeeze, divers are trained to exhale air out through the nose and thus balance the pressure by increasing the amount of air inside the mask. Injury can occur if the diver does not compensate or xe2x80x9cequalizexe2x80x9d mask pressure in this way. The injuries are typically minor, manifesting themselves as red marks on the face or burst blood vessels in the nose (nosebleeds) or on the surface of the eye (eye-squeeze). In more extreme cases, eyes have been pulled from their sockets, sometimes resulting in permanent blindness. In spite of formal training (which is only a requirement for SCUBA diving certification and not for snorkelers), mask squeeze related injury is a fairly common occurrence. It is easy to be distracted and forget about mask equalization in spite of pain and discomfort.
From the above-discussion, it can be seen that a need exists for a dive mask capable of providing an automatic limitation on the pressure differential between the air inside the mask and the water outside of it. Such a device would enable beginning divers to avoid injury without the need to constantly monitor and adjust the pressure of the mask interior, and would protect even experienced divers in the case of distractions, injury,
In view of the foregoing, it is a primary object of the present invention to provide a pressure relief device capable of maintaining the pressure differential across the dive mask at or below a preset level. Consistent with this object, and in accordance with the invention as embodied and broadly described herein, an apparatus and method are disclosed, in suitable detail to enable one of ordinary skill in the art to make and use the invention.
In certain embodiments an apparatus and method in accordance with the present invention may comprise a dive mask pressure relief device. In one embodiment of the present invention, a predetermined pressure differential is maintained by a sealable ingress port and an actuator. The actuator is operably connected with the sealable ingress port to selectively allow outside ambient fluid to pass through the sealable ingress port when pressure outside the dive mask exceeds pressure inside the dive mask by a selected amount.
The dive mask pressure relief device may include additional features to make the pressure control device easier and more convenient to use. For example, an adjustment mechanism can be provided in conjunction with the pressure control device so that the diver can select the maximum allowable pressure differential. A manual release may be included so that the diver can manually allow water into the mask without breaking the mask""s perimeter seal. The device can also be incorporated with a purging device to permit rapid evacuation of water from the mask after pressure equalization. Finally, the invention may comprise a bubble diverter designed to keep air bubbles ejected from the mask from obscuring the diver""s vision.
In a preferred embodiment of the invention, the pressure relief device is formed by providing an opening in the outer surface of the dive mask. A spring-loaded plugging member or xe2x80x9ccorexe2x80x9d prevents water from entering the opening unless the pressure differential becomes great enough to overcome the force of the spring. In accordance with one contemplated embodiment, the diver can adjust the pressure differential required to permit flow through the opening by adjusting the compression of the spring. In another contemplated embodiment, the diver can manually displace the core from the opening by pressing on a member extending from the core to move the core out of the opening.
A further embodiment permits selective purging of water from the mask by providing an orifice in the core; the orifice is closed unless the diver supplies a higher air pressure in the mask to deflect a flexible flap covering the orifice. An additional embodiment prevents bubbles ejected from the mask during purging from obscuring the diver""s vision by providing an enclosure with an angled outlet to channel the bubbles away from the lens of the mask. The advances embodied herein can be combined and used together within the scope and spirit of the invention.